A ring binder typically holds sheets of a common form of notebook paper with typically two or three perforated ring apertures. A like number of rings are secured to a binder central strip that in turn is secured to the spine of a folder, or cover, having front and rear sides, the totality of binder strip, ring structure, and folder comprising the ring binder. The rings can be rotated to open and closed positions. In the open position a number of the perforated sheets are slid onto the rings and the rings then rotated to the closed position so as to make a notebook or a book. One type of ring binder includes a binder strip secured to the spine of a folder and a separate ring structure that is separately mounted to the binder strip. Another type of ring binder includes a binder with a binder strip unitary with a ring structure both secured to the spine of a folder, the unitary binder and ring structure being made of a flexible plastic with the ring structures being individually movable, or flexed, between the open and closed positions.
The securing of a binder strip with a separate ring structure with a folder or a unitary binder strip and ring structure with a folder is generally done by a mass assembly apparatus that is unsuitable to short-run production using offset-printed custom folders.